. Atherosclerotic plaques (atheromas) in the aortic arch are considered a potential cause for ischemic stroke in the elderly. The impact of arch atheromas in different racial-ethnic groups is unknown. Moreover, the association of arch atheromas with lipid disorders or hypercoagulability, that may enhance their embolic potential, has not been investigated. A population-based, case-control study is proposed to address the following Specific Aims: 1) to determine if aortic arch atheromas are a risk factor for ischemic stroke in the elderly, and their importance in different racial-ethnic subgroups; and 2) to determine if aortic arch atheromas are associated with lipid abnormalities or hypercoagulable states in elderly stroke patients. Secondary Aims will be to evaluate the 4-year stroke recurrence risk in patients with and without atheromas in the overall group and by racial-ethnic subgroups, and the additional risk associated with morphological characteristics of the atheroma (presence of ulcerations or mobile components). A total of 300 cases of ischemic stroke and 300 stroke-free controls, matched by age, gender and race will be enrolled in this 5-year population-based case-control study. Study subjects will be drawn from the ongoing Northern Manhattan Stroke Study (NoMaSS), which will assure recruitment and provide other data collection. The presence of arch atheromas will be ascertained by transesophageal echocardiography. Lipid tests will include total cholesterol, triglycerides, HDL and LDL cholesterol, lipoprotein (a), apolipoproteins A-I and B. Hypercoagulability tests will include fibrinogen, prothrombin fragment F1+2 and lupus anticoagulant. Annual telephone follow-up will be performed on cases and controls to ascertain mortality and stroke. Conditional logistic regression will be used to calculate the adjusted odds ratio for stroke of aortic arch atheromas in the overall study group and stratified by racial-ethnic subgroups. The study will provide important data on stroke pathophysiology and set the ground for clinical trials to assess the efficacy of therapeutic options in treating elderly patients with stroke and aortic arch atheromas.